The present invention relates to portable power tools in general, especially to so-called impact type power tools wherein a reciprocable tool is struck by an impeller, and more particularly to improvements in portable power tools wherein the tool (such as a rock drill or chisel) receives motion from a fluid-operated motor. Still more particularly, the invention relates to improvements in portable power tools wherein a rotary and/or reciprocable tool receives motion from a hydraulic motor.
It is already known to provide a portable impact hammer with an impeller which is reciprocable by pressurized hydraulic fluid so that it performs alternating forward and return strokes and strikes against a tool during each of its forward strokes. The fluid is pressurized in a discrete aggregate having a pump which is driven by an electric motor or by a combustion engine and whose outlet is connected with the power tool by a flexible conduit. Another flexible conduit connects the housing of the power tool with a reservoir for hydraulic fluid.
A drawback of the just described power tools is that they are costly, complex, bulky and require frequent maintenance. Also, their efficiency is relatively low, especially due to leakage of hydraulic fluid which must be conveyed through several elongated flexible conduits, and also due to elasticity of such conduits. Moreover, the power tools as well as the aforementioned aggregates are noisy and the maximum distance between the power tool proper and the aggregate which supplies pressurized hydraulic fluid is relatively short. Still further, the versatility of conventional hydraulically operated portable power tools is rather limited.